1. Field of the Invention
The present invention relates to an image scanning apparatus and method for scanning an image on, e.g., a transparent original (also called a transmissive original) such as a developed photographic film or the like, an opaque film original, or the like.
2. Description of the Related Art
The arrangement of a conventional film scanner will be explained below with reference to FIGS. 44 to 46.
FIG. 44 is a perspective view showing principal part of a conventional film scanner, FIG. 45 is a schematic view showing the arrangement of the film scanner shown in FIG. 44, and FIG. 46 is a block diagram showing the circuit arrangement of the film scanner shown in FIG. 44.
Referring to FIGS. 44 to 46, reference numeral 501 denotes a film carriage used as a platen; and 502, a developed film which is fixed on the film carriage 501. Reference numeral 503 denotes a lamp serving as a light source; 504, a mirror; 505, a lens; and 506, a line sensor comprising, e.g., a CCD and the like. Light emitted by the lamp 503 is transmitted through the film 502, is reflected by the mirror 504, and forms an image on the line sensor 506 by the lens 505.
Reference numeral 507 denotes a motor for moving the film carriage 501 in the scan direction (the direction of the arrow in FIGS. 44 and 45); 508, a sensor for detecting the position of the film carriage 501; 509, an optical axis extending from the lamp 503 o the line sensor 506; 510, a control circuit; 511, a lens holder for holding the lens 505; 512, an outer case of the film scanner; and 513, an input/output terminal.
The lamp 503, line sensor 506, motor 507, sensor 508, and input/output terminal 513 are electrically connected to the control circuit 510. The control circuit 510 comprises a film scanner control circuit, sensor control circuit, motor control circuit, image information processing circuit, lamp control circuit, line sensor control circuit, film density detection circuit, and motor drive speed determination circuit, as shown in FIG. 46.
An image information scanning method of the film 502 will be explained below.
Upon receiving a film scan command from an external device via the input/output terminal 513, the sensor 508 and sensor control circuit detect the position of the film carriage 501, and that information is sent to the film scanner control circuit. The motor control circuit drives the motor 507 to set the film carriage 501 at a predetermined standby position, thus moving the film carriage 501 to the standby position. The film density detection circuit detects the density of the film 502 by a known method, and the motor drive speed determination circuit determines the drive speed of the motor 507 for a scan on the basis of the density information. The lamp control circuit turns on the lamp 503, and the motor 507 is rotated at the determined drive speed, thus scanning the film. During the scan, the line sensor 506 sends image information to the image information processing circuit via the line sensor control circuit. Upon completion of the scan, the lamp control circuit turns off the lamp 503, and at the same time, the image information processing circuit executes image information processing. The obtained image information is then output from the input/output terminal 513, thus ending film image scanning of the film scanner.
In recent years, a film scanner which scans the film not only using visible light, as described above, but also using infrared light to detect dust or scratches on the film, superimposes the detected dust or scratch image information on the image information obtained by a scan using the visible light, and corrects it by image processing has been proposed by, e.g., Japanese Patent Publication No. 06-78992, and the like.
However, since such prior art requires a memory for storing film image information obtained by infrared light, a larger memory size than the aforementioned prior art is required. When a film image is scanned with infrared light to correct dust or scratches on the film, the required scan time is prolonged accordingly.